python_runtime "2" is broken on a ubuntu 16.04 system with Chef 12. When python_runtime is executing, pip 19.0.1 is installed and the internals have changed a lot since pip 18.x. Any attempt to locate setuptools, wheel, etc is met with AttributeError: Values instance has no attribute 'process_dependency_links'. process_dependency_links option has been removed in pip 19 and this line causes the issue: https://github.com/poise/poise-python/blob/master/lib/poise_python/resources/python_package.rb#L73.

Once you remove the option, there's another breakage with req = InstallRequirement.from_line(arg). This line seems to have changed with a later, unreleased version of poise-python (changed after 1.7.0).